A black compound of manganese reacts with a halogen acid to give greenish-yellow gas. When an excess of this gas reacts with ${\mathrm{NH}}_3$ an unstable trihalide is formed. In this process, the oxidation state of nitrogen changes from-

1. –3 to +3

2. –3 to 0

3. –3 to +5

4. 0 to –3

Reduction potentials of some ions are given below. Arrange them in decreasing order of oxidising power.

$1. {\mathrm{ClO}}_4^{-} > {\mathrm{IO}}_4^{-} > {\mathrm{BrO}}_4^{-}$
$2. {\mathrm{IO}}_4^{-} > {\mathrm{BrO}}_4^{-} > {\mathrm{ClO}}_4^{-}$
$3. {\mathrm{BrO}}_4^{-} > {\mathrm{IO}}_4^{-} > {\mathrm{ClO}}_4^{-}$
$4. {\mathrm{BrO}}_4^{-} > {\mathrm{ClO}}_4^{-} > {\mathrm{IO}}_4^{-}$

If chlorine gas is passed through a hot NaOH solution, two changes are observed in the oxidation number of chlorine during the reaction. These are ......... and  .............

a. 0 to +5

b. 0 to +3

c. 0 to -1

d. 0 to +1

Choose the correct option:

1. (a, b)
2. (b, c)
3. (c, d)
4. (a, c)

Which of the following statements are correct?

1. (a, b, c)
2. (b, c, d)
3. (a, c, d)
4. (a, b, d)

Which of the following orders are correct as per the properties mentioned against each?

1. (a, b)
2. (b, c)
3. (c, d)
4. (a, d)

Match the formulas of oxides are given in Column I with the type of oxide given in Column II and mark the correct option.

Codes:

Match the species given in Column I with the shape given in Column II and mark the correct option.

Codes

On addition of conc. $H_{2}S{O}_4$ to a chloride salt, colourless fumes are evolved but in case of iodide salt, violet fumes come out. This is because: